1. Field of the Invention
This invention relates to an ignition timing control system for internal combustion engines, and more particularly to an ignition timing system for vehicle internal combustion engines which conducts ignition timing retard control during acceleration so as to eliminate vibration of the vehicle body.
2. Description of the Prior Art
There have been proposed ignition timing control systems for vehicle internal combustion engines in which ignition timing is retarded during acceleration so as to prevent combustion knock. One example of such a system is described in Japanese Laid-open Patent Publication No. 57(1982)-99269. In this prior art system, when acceleration is detected, the ignition timing is retarded by a predetermined amount so as to avoid knocking.
While the aforesaid system retards the ignition timing for the purpose of preventing knocking during acceleration, there also arises another problem in a vehicle having a relatively highpowered engine with a manual transmission when the vehicle accelerates. Specifically, in such a vehicle the vehicle body is unable to keep pace with the rapid change in the output torque of the vehicle engine so that a torque phase lag arises. This produces twisting in the drive system for transmitting the output to the drive wheels, particularly in the drive shaft, which in turn produces vibration that not only adversely affects the feeling experienced by the operator during acceleration but also degrades the drivability.